Etched recess package on package system

ABSTRACT

An integrated circuit package system includes: interconnection pads; a first device mounted below the interconnection pads; a bond wire, or a solder ball connecting the first device to the interconnection pads; a lead connected to the interconnection pad or to the first device; an encapsulation having a top surface encapsulating the first device; and a recess in the top surface of the encapsulation with the interconnection pads exposed therefrom.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This is a divisional of U.S. patent application Ser. No. 12/185,058 filed Aug. 1, 2008, now U.S. Pat. No. 7,932,130.

TECHNICAL FIELD

The present invention relates generally to integrated circuits and more particularly to a system for utilizing an etched recess in a package on package system.

BACKGROUND ART

The rapidly growing portable electronics market, e.g. cellular phones, laptop computers, and PDAs, are an integral facet of modern life. The multitude of portable devices represents one of the largest potential market opportunities for next generation packaging. These devices have unique attributes that have significant impacts on manufacturing integration, in that they must be generally small, lightweight, and rich in functionality and they must be produced in high volumes at relatively low cost.

As an extension of the semiconductor industry, the electronics packaging industry has witnessed ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace.

Packaging, materials engineering, and development are at the very core of these next generation electronics insertion strategies outlined in road maps for development of next generation products. Future electronic systems may be more intelligent, have higher density, use less power, operate at higher speed, and may include mixed technology devices and assembly structures at lower cost than today.

Current packaging suppliers are struggling to accommodate the high-speed computer devices that are projected to exceed one TeraHertz (THz) in the near future. The current technologies, materials, equipment, and structures offer challenges to the basic assembly of these new devices while still not adequately addressing cooling and reliability concerns.

The envelope of technical capability of next level interconnect assemblies are not yet known, and no clear cost effective technology has yet been identified. Beyond the performance requirements of next generation devices, the industry now demands that cost be a primary product differentiator in an attempt to meet profit goals.

As a result, the road maps are driving electronics packaging to precision, ultra miniature form factors, which require automation in order to achieve acceptable yield. These challenges demand not only automation of manufacturing, but also the automation of data flow and information to the production manager and customer.

There have been many approaches to addressing the advanced packaging requirements of microprocessors and portable electronics with successive generations of semiconductors. Many industry road maps have identified significant gaps between the current semiconductor capability and the available supporting electronic packaging technologies. The limitations and issues with current technologies include increasing clock rates, EMI radiation, thermal loads, second level assembly reliability stresses, and cost.

As these package systems evolve to incorporate more components with varied environmental needs, the pressure to push the technological envelope becomes increasingly challenging. More significantly, with the ever-increasing complexity, the potential risk of error increases greatly during manufacture.

In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to reduce costs, reduce production time, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.

Thus, a need remains for smaller footprints and more robust packages and methods for manufacture. Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.

DISCLOSURE OF THE INVENTION

The present invention provides an integrated circuit package system including: interconnection pads; a first device mounted below the interconnection pads; a bond wire, or a solder ball connecting the first device to the interconnection pads; a lead connected to the interconnection pad or to the first device; an encapsulation having a top surface encapsulating the first device; and a recess in the top surface of the encapsulation with the interconnection pads exposed therefrom.

Certain embodiments of the invention have other aspects in addition to or in place of those mentioned above. The aspects will become apparent to those skilled in the art from a reading of the following detailed description when taken with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of an integrated circuit package system in a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the integrated circuit package system along the line 2-2 of FIG. 1;

FIG. 3 a cross-sectional view of the integrated circuit package system of FIG. 2 in a pre-etch phase of manufacture;

FIG. 4 is the integrated circuit package system of FIG. 2 in a post-etch phase of manufacture;

FIG. 5 is a cross-sectional view of an integrated circuit package system in a second embodiment of the present invention; and

FIG. 6 is a flow chart of a system for manufacturing the integrated circuit package system of FIG. 1 in an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following embodiments are described in sufficient detail to enable those skilled in the art to make and use the invention. It is to be understood that other embodiments would be evident based on the present disclosure, and that system, process, or mechanical changes may be made without departing from the scope of the present invention.

In the following description, numerous specific details are given to provide a thorough understanding of the invention. However, it will be apparent that the invention may be practiced without these specific details. In order to avoid obscuring the present invention, some well-known circuits, system configurations, and process steps are not disclosed in detail.

Likewise, the drawings showing embodiments of the system are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown greatly exaggerated in the drawing FIGs. The same numbers are used in all the drawing FIGs. to relate to the same elements.

For expository purposes, the term “horizontal” as used herein is defined as a plane parallel to the plane or surface of the integrated circuit, regardless of its orientation. The term “vertical” refers to a direction perpendicular to the horizontal as just defined. Terms, such as “above”, “below”, “bottom”, “top”, “side” (as in “sidewall”), “higher”, “lower”, “upper”, “over”, and “under”, are defined with respect to the horizontal plane. The term “on” means that there is direct contact among elements.

The term “processing” as used herein includes deposition of material or photoresist, patterning, exposure, development, etching, cleaning, and/or removal of the material or photoresist as required in forming a described structure. The term “system” as used herein refers to and is defined as the method and as the apparatus of the present invention in accordance with the context in which the term is used.

Referring now to FIG. 1, therein is shown a top view of an integrated circuit package system 100 in a first embodiment of the present invention. The integrated circuit package system 100 is shown having an encapsulation 102 such as an epoxy mould compound. The encapsulation 102 has an encapsulation edge 104.

At the edge 104 of the encapsulation 102 are leads 106. The leads 106 do not extend substantially beyond the edge 104 of the encapsulation 102. The encapsulation 102 fills spaces 108 in between the leads 106.

A second device 110 such as a wafer level chip scale package (WLCSP), a redistributed line (RDL) die, or an area array package is shown mounted above the encapsulation 102. Around an outer edge 112 of the second device 110 is a recess 114. The second device 110 is mounted inside the recess 114.

Referring now to FIG. 2, therein is shown a cross-sectional view of the integrated circuit package system 100 along the line 2-2 of FIG. 1. The integrated circuit package system 100 is shown having first device 202 such as a wire-bonded die. The first device 202 has an active side 204.

The active side 204 of the first device 202 is connected to interconnection pads 206. The interconnection pads 206 are coated or composed substantially of NiPd—Au. This nickel palladium and gold composition resists copper etching and allows the formation of the recess 114.

It has been unexpectedly discovered that the use of the interconnection pads 206 enables an electrical connection of the first device 202 without added structural elements such as interposers and substrates. This allows for a very thin package by reducing the number of internal components.

The active side 204 of the first device 202 is connected to the interconnection pads 206 with bond wires 208. The bond wires 208 are in direct contact with to the first device 202 and in direct contact with the interconnection pads 206 from one end to the other end of the bond wire. The encapsulation 102 encapsulates the bond wires 208. The encapsulation also adds structural support by filling spaces 210 in between the interconnection pads 206.

The first device 202 is attached to a die pad 212 with die attach adhesive 214. The die pad is coated or composed substantially of NiPd—Au. The die attach adhesive 214 should be a high thermally conductive adhesive to allow the first device 202 to shed heat through the die pad 212. The die pad 212 is coplanar with and spaced away from the interconnection pads 206.

The encapsulation 102 forms a rigid structure around the interconnection pads 206, the bond wires 208, and the first device 202. It has been unexpectedly discovered that the use of the encapsulation 102 as a rigid structure containing and supporting the interconnection pads 206, the bond wires 208, and the first device 202, reduces the complexity and number of internal components. The result being higher end-line yields, reduced costs, and competitive reduction in package size.

The encapsulation 102 also partially contains and partially surrounds the leads 106. The leads 106 are coated or composed substantially of NiPd—Au. The leads 106 are encapsulated by a top surface 220 of the encapsulation 102. The top surface 220 of the encapsulation is over the first device 202.

The leads 106 are connected to the interconnection pads 206 with the bond wires 208. The bond wires 208 are fully encapsulated by the encapsulation 102. Mounted in the recess 114, external to the encapsulation 102, is the second device 110.

The recess 114 further contributes to the thin dimensions of the package. Because of the absence of structural components such as interposers or substrates, the second device 110 may be mounted closer to the first device 202.

It has been unexpectedly discovered that mounting the first device 202 closer to the second device 110 reduces parasitic inductance. The reduction in distance reduces the inductance generated in high-speed components that can reduce the performance of the package as a whole, thus increasing the operating parameters of the first device 202 and the second device 110.

The second device 110 is connected to the interconnection pads 206 with interconnects such as metal connection pads 222 attached to the second device 110 and the interconnection pads 206. The second device 110 is shown having a second wire-bonded die 224 with an active side 226.

The active side 226 is connected to the metal connection pads 222 with the bond wires 208. The wire-bonded die 224 is attached to a second die pad 228 with the die attach adhesive 214. Encapsulating the second wire-bonded die 224 is a second encapsulation 230.

Referring now to FIG. 3, therein is shown the cross-sectional view of the integrated circuit package system 100 of FIG. 2 in a pre-etch phase of manufacture. The integrated circuit package system 100 is shown having a die attach paddle 302 such as a copper die attach paddle.

The die attach paddle 302 has the interconnection pads 206 connected to a bottom surface 304 of the die attach paddle 302. The die attach paddle 302 is exposed on the top surface 220 of the encapsulation 102. The NiPd—Au is resistant to Copper etching, which will leave the leads 106 and the interconnection pads 206 remaining after a copper etch has etched the die attach paddle 302. This result may also be accomplished by a selective etching only the die attach paddle 302 in the recess 114.

Referring now to FIG. 4, therein is shown the integrated circuit package system 100 of FIG. 2 in a post-etch phase of manufacture. The integrated circuit package system 100 is shown having the recess 114 created near the top surface of the encapsulation 102.

The interconnection pads 206 are now exposed in the recess 114 and in direct contact with the encapsulation 102 separating the interconnection pads 206 from the leads 106. The interconnection pads 206 are between the leads 106 and the die pad 212 of FIG. 2. The leads 106 can have a top planar surface 401 and a bottom planar surface 403 above the interconnection pads 206. The encapsulation 102 between the spaces 210 of the interconnection pads 206 is also exposed.

Referring now to FIG. 5, therein is shown a cross-sectional view of an integrated circuit package system 500 in a second embodiment of the present invention. The integrated circuit package system 500 is shown having first device 502 such as a flip chip. The first device 502 has an active side 504.

The active side 504 of the first device 502 is connected to interconnection pads 506. The solder balls 512 are attached to the first device 502 and the interconnection pads 506. The interconnection pads 506 are coated or composed substantially of NiPd—Au. This nickel palladium and gold composition resists copper etching and allows the formation of a recess 508.

It has been unexpectedly discovered that the use of the interconnection pads 506 enables an electrical connection of the first device 502 without added structural elements such as interposers and substrates. This allows for a very thin package by reducing the number of internal components.

The active side 504 of the first device 502 is connected to the interconnection pads 506 with interconnects such as solder balls 512. An encapsulation 514, such as an epoxy mold compound, encapsulates the solder balls 512. The encapsulation also adds structural support by filling spaces 516 in between the interconnection pads 506.

The encapsulation 514 forms a rigid structure around the interconnection pads 506, the solder balls 512, and the first device 502. It has been unexpectedly discovered that the use of the encapsulation 514 as a rigid structure containing and supporting the interconnection pads 506, the solder balls 512, and the first device 502, reduces the complexity and number of internal components. The result being higher end-line yields, reduced costs, and competitive reduction in package size.

The encapsulation 514 also partially contains and partially surrounds leads such as leads 518. The leads 518 are coated or composed substantially of NiPd—Au. The leads 518 are exposed from a top surface 520 of the encapsulation 514.

The leads 518 are connected to the interconnection pads 506 with bond wires 524. The bond wires 524 are fully encapsulated by the encapsulation 514. Mounted in the recess 508, external to the encapsulation 514, is a second device 526 such as a wafer level chip scale package (WLCSP), a redistributed line (RDL) die, or an area array package.

The recess 508 further contributes to the thin dimensions of the package. Because of the absence of structural components such as interposers or substrates, the second device 526 may be mounted closer to the first device 502.

It has been unexpectedly discovered that mounting the first device 502 closer to the second device 526 reduces parasitic inductance. The reduction in distance reduces the inductance generated in high-speed components that can reduce the performance of the package as a whole, thus increasing the operating parameters of the first device 502 and the second device 526.

The second device 526 is connected to the interconnection pads 506 with the solder balls 512 attached to the second device 526 and the interconnection pads 506. Mounted above the second device 526 is a third device 528 such as a wafer level chip scale package (WLCSP), a redistributed line (RDL) die, or an area array package.

The third device 528 is connected to the leads 518 with the solder balls 512.

Referring now to FIG. 6, therein is shown a flow chart of a system 600 for manufacturing the integrated circuit package system 100 of FIG. 1 in an embodiment of the present invention. The system 600 includes providing a die attach paddle with interconnection pads connected to a bottom surface of the die attach paddle in a block 602; connecting a first device to the interconnection pads with a bond wire in a block 604; connecting a lead to the interconnection pad or to the first device in a block 606; encapsulating the first device and the die attach paddle with an encapsulation having a top surface in a block 608; and etching the die attach paddle leaving a recess in the top surface of the encapsulation in a block 610.

Thus, it has been discovered that the etched recess system of the present invention furnishes important and heretofore unknown and unavailable solutions, capabilities, and functional aspects for package on package configurations. The resulting processes and configurations are straightforward, cost-effective, uncomplicated, highly versatile, accurate, sensitive, and effective, and can be implemented by adapting known components for ready, efficient, and economical manufacturing, application, and utilization.

While the invention has been described in conjunction with a specific best mode, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the included claims. All matters hithertofore set forth herein or shown in the accompanying drawings are to be interpreted in an illustrative and non-limiting sense. 

What is claimed is:
 1. An integrated circuit package system comprising: a die pad; an interconnection pad coplanar with and spaced away from the die pad; a first device mounted on the die pad and below the interconnection pad; a bond wire or a solder ball in direct contact with the first device and in direct contact with the interconnection pad; a lead having a top planar surface and a bottom planar surface, the lead isolated from the interconnection pad and connected to the first device, the interconnection pad between the lead and the die pad; and an encapsulation having a top surface over the first device and a recess in the top surface of the encapsulation with the interconnection pad exposed within the recess, the interconnection pad in direct contact with the encapsulation, the interconnection pad separated from, the lead by the encapsulation, and the bottom planar surface above the interconnection pad.
 2. The system as claimed in claim 1 wherein: the lead is exposed from the top surface of the encapsulation.
 3. The system as claimed in claim 1 wherein: the lead is encapsulated by the top surface of the encapsulation.
 4. The system as claimed in claim 1 wherein: the first device is a wire-bonded die or a flip chip.
 5. The system as claimed in claim 1 further comprising: a second device mounted above the interconnection pad; and an interconnect attached to the second device and the interconnection pad.
 6. The system as claimed in claim 5 further comprising: a third device attached to the lead exposed from the top surface of the encapsulation.
 7. The system as claimed in claim 5 wherein: a metal connection pad or solder ball attached to the second device and the interconnection pad.
 8. The system as claimed in claim 5 wherein: the interconnection pad is coated or composed substantially of nickel, palladium, and gold.
 9. The system as claimed in claim 5 wherein: the lead is coated or composed substantially of nickel, palladium, and gold.
 10. The system as claimed in claim 5 wherein: the second device is mounted inside the recess. 